Broken engine mount bolts.

[LAWALLSTRACTOR]

Hi everbody,
I usually try to help others here, but now need some assistance myself. After 8 years with Mahindra, I have run into my first instance of broken off engine mount bolts. I found the problem when doing routine service on a Mahindra 2810 HST. I called my customer and told him I had found 2 broken off bolts and that I thought they should be replaced. He agreed and told me that he had found them loose before and had removed them and put them back in with locktite. The bolts are a M12 with 1.25 thread and they are a hardened bolt. They are broken off at about 1/4" into about the engine block. Considering the outer 1/4" of threads in the block are damaged, I thought that the course of action should be to drill out the whole bolt, rethread the hole and replace the bolt. I heated the bolt left in the hole to remove the temper in the bolt, but I still can't drill it . Does anyone have any suggestions. Any help would be greatly appreciated.

[Outlander]

Carbide drill bit should do it. Go slow and lubricate. Carbide bits can be a tad brittle.

[tommu56]

LAWALLSTRACTOR
I' try a bottoming tap in the hole to fix the threads that are damaged and then try and turn it out.

Heat it again and quench it with water that might take temper out.

carbide like Outlander suggested.
start small on the regular bits 1/8" is a good start size.

I like to use sheet metal bits short shank and short flute = stronger bits.

We had a sales guy in selling some super duper welding rods and he put a nut over the hole just like you described and ran a bead of weld on what was left of the bolt and up inside the nut and he just spun out the bolt with the nut.
I never was that good of a welder but he had that "demonstration down pat".

tom

[thomass38]

Originally Posted by LAWALLSTRACTOR

Hi everbody,
I usually try to help others here, but now need some assistance myself. After 8 years with Mahindra, I have run into my first instance of broken off engine mount bolts. I found the problem when doing routine service on a Mahindra 2810 HST. I called my customer and told him I had found 2 broken off bolts and that I thought they should be replaced. He agreed and told me that he had found them loose before and had removed them and put them back in with locktite. The bolts are a M12 with 1.25 thread and they are a hardened bolt. They are broken off at about 1/4" into about the engine block. Considering the outer 1/4" of threads in the block are damaged, I thought that the course of action should be to drill out the whole bolt, rethread the hole and replace the bolt. I heated the bolt left in the hole to remove the temper in the bolt, but I still can't drill it . Does anyone have any suggestions. Any help would be greatly appreciated.

I also have a 2810hst and would like to know which bolts broke. I would like to check my bolts to make sure they are tight.
Thanks TOM

[Gator6x4]

One trick I have seen used to extract a broken bolt was grind a small nut into a round nut so that it will fit into the hole where the broken bolt is. Weld the nut to the bolt and then weld another nut to this to provided something for a wrench to turn. The heat from the welding also helps in loosing the bolt. The use of locktite on the bolt will make extraction even harder. This is why you probably got the "JOB". Good luck.

[bindian]

Galen,
Carbide bits are real brittle. I prefer cobalt bits over carbide bits. I have Boelube lubricant I use for drilling steel. It is like a wax and is the cat's meow for cooling and lubricating steel while drilling. BOELUBE PRODUCTS from Aircraft Spruce It was designed for drilling titanium on the B-58 bomber. With the locktite, heat will be needed for sure. Just a propane torch worked for my broken bolt (approx. 3/4 inch diameter) on my backhoe subframe. I would not quench it with anything, since you are in an engine block and quenching is used for hardening. I gather this is about a 7/16th inch diameter bolt?
hugs, Brandi

[AHNC]

I had this happen on a Mercedes block many years ago. I had no money and had to fix it myself. Lots of Boelube and a raft of 1/8" cobalt bits as suggested. Get comfortable because you will likely be there for a while. Don't get impatient and drill to shallow a hole as the easy out may snap off and then, well, it isn't pretty.

[bindian]

Galen,
With the Boelube block, just drill a little to get the bit warm, then dip it into the block. Keep doing this every 5 or so seconds.
hugs and Good Luck, Brandi

[MississippiMan]

Seems to be a lot of stuff breaking off of people's Mahindras lately.

[bindian]

Originally Posted by MississippiMan

Seems to be a lot of stuff breaking off of people's Mahindras lately.

MississippiMan,
I guess a lot of folks are working their Mahindras as hard as I do. If they were lighter in weight like the competition, there would a lot more breakdowns.
hugs, Brandi